It is conventional that, in DAB (Digital Audio Broadcasting), at the transmission side the overall frequency spectrum of the digital audio signals to be transmitted is divided into frequency ranges. These frequency ranges are called subbands. Per subband, a maximum of 3 scale factors are defined as reference values. In each subband, in the case of stereo transmissions 36 sampling values are produced in chronologically successive fashion per channel. The 36 sampling values are divided into groups, chronologically separated from one another, of 12 sampling values each. Per group, a maximum of one scale factor is defined. If two, or all three, scale factors of a subband are equal, or at least with very similar values, then only one scale factor is transmitted for the scale factors. Within a DAB frame in which the sampling values and their scale factors are transmitted, it is thus signaled for which group or groups of sampling values for a subband a respective scale factor is to be used. In each group or groups of sampling values, the scale factors have the largest signal power value. The remaining signal values in this group or in these groups are normed to this scale factor.
In the receiver, error recognition and correction methods are then performed during the source decoding, after such methods have been executed in a preceding channel decoding. These error recognition and correction methods during the source decoding relate both to the DAB frames and to the scale factors. The digital audio data are then denormed using the scale factors, and a decoding of the audio data occurs.
In U.S. Pat. No. 5,706,396, a comparison of the transition of scale factors in the decoding is described. Here, a threshold value comparison, a comparison with an expected transition, or a polarity comparison is performed. German Published Patent Application No. 44 09 960 refers to determining error recognition in digital audio data, given scale factors, using a check sum, i.e., CRC, and to using error masking measures dependent on this error recognition. In U.S. Pat. No. 4,831,624, an error recognition using CRC is described.